Google Data

Posted by Murray Stokely, Google Storage Analytics Team

This year marks Google’s eleventh consecutive year as a sponsor of the USENIX Annual Technical Conference (ATC), just one of the co-located events at USENIX Federated Conference Week (FCW), which combines numerous conferences and workshops covering fields such as Autonomic Computing, Feedback Computing and much more in an intensive week of research, trends, and community interaction.

ATC provides a broad forum for computing systems research with an emphasis on implementations and experimental results. In addition to the Googlers presenting publications, we had two members on the program committee of ATC and several keynote speakers, invited speakers, panelists, committee members, and participants at the other co-located events at FCW.

In the paper Janus: Optimal Flash Provisioning for Cloud Storage Workloads, Googler Christoph Albrecht and co-authors demonstrated a system that allows users to make informed flash memory provisioning and partitioning decisions in cloud-scale distributed file systems that include both flash storage and disk tiers. As flash memory is still expensive, it is best to use it only for workloads that can make good use of it. Janus creates long term workload characterizations based on RPC samples and file age metadata. It uses these workload characterizations to formulate and solve an optimization problem that maximizes the reads sent to the flash tier. Based on evaluations from workloads using Janus, in use at Google for the past 6 months, the authors conclude that the recommendation system is quite effective, with flash hit rates using the optimized recommendations 47-76% higher than the option of using the flash as an unpartitioned tier.

In packetdrill: Scriptable Network Stack Testing, from Sockets to Packets, Google’s Neal Cardwell and co-authors showcased a portable, open-source scripting tool that enables testing the correctness and performance of network protocols. Despite their importance in modern computer systems, network protocols often undergo only ad hoc testing before their deployment, in large part due to their complexity. Furthermore, new algorithms have unforeseen interactions with other features, so testing has only become more daunting as TCP has evolved. The packetdrill tool was instrumental in the development of three new features for Linux TCP—Early Retransmit, Fast Open, and Loss Probes—and allowed the authors to find and fix 10 bugs in Linux. Furthermore, the team uses packetdrill in all phases of the development process for the kernel used in one of the world’s largest Linux installations. In the hope that sharing packetdrill with the community will make the process of improving Internet protocols an easier one, the source code and test scripts for packetdrill have been made freely available.

There were also additional refereed publications with Google co-authors at some of the co-located events at FCW, notably NicPic: Scalable and Accurate End-Host Rate Limiting, which outlines a system which enables accurate network traffic scheduling in a scalable fashion, and AGILE: Elastic Distributed Resource Scaling for Infrastructure-as-a-Service, a system that efficiently handles dynamic application workloads, reducing both penalties and user dissatisfaction.

Google is proud to support the academic community through conference participation and sponsorship. In particular, we are happy to mention one of the other interesting papers from this year’s USENIX FCW, co-authored by former Google PhD fellowship recipient Ashok Anand, MiG: Efficient Migration of Desktop VM Using Semantic Compression.

USENIX is a supporter of open access, so the papers and videos from the talks are available on the conference website.